Oscillator

ABSTRACT

An oscillator that can suppress a solder crack caused by a temperature change by a simple structure at low cost and improve heat cycle resistance performance is provided. The oscillator includes an epoxy resin board and an electronic component mounted on the board. Two-terminal electrode patterns are formed on the board, and connected to terminal electrodes of the electronic component by solder. A projection is formed on each of the electrode patterns at a part connected to a corresponding terminal electrode to create a space between the terminal electrode and the electrode pattern, and the solder forms a fillet in the space. This contributes to enhanced adhesion strength of the solder.

This application has a priority of Japanese no. 2011-023575 filed Feb.7, 2011, no. 2011-028223 filed Feb. 14, 2011, no. 2011-068064 filed Mar.25, 2011 and no. 2011-152916 filed Jul. 11, 2011, hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an oscillator using a circuit board ofa glass epoxy resin, and particularly relates to an oscillator thatrelaxes strain on solder and improves heat cycle resistance performance.

2. Description of the Related Art

PRIOR ART

Conventionally, there is a crystal oscillator that uses a glass epoxyresin in a circuit board. Metal electrode patterns are formed on thecircuit board, and an electronic component of ceramic or the like ismounted on the electrode patterns by soldering.

[Conventional Crystal Oscillator: FIG. 22]

A conventional crystal oscillator is described below, with reference toFIG. 22. FIG. 22A is a plan view of the conventional crystal oscillator,and FIG. 22B is a section view of the conventional crystal oscillator.

As shown in FIG. 22, in the conventional crystal oscillator, metalpattern wires 4 are formed on a circuit board (board) 1 of a glass epoxyresin, and an electronic component 2 having two terminal electrodes 3 ismounted on the board 1. For example, the electronic component 2 is acrystal resonator, a resistor, or the like.

In particular, the terminal electrodes 3 and the pattern wires 4 arebonded by solder 5.

[Another Conventional Crystal Oscillator: FIG. 23]

Another conventional crystal oscillator is described below, withreference to FIG. 23. FIG. 23 is a section view of another conventionalcrystal oscillator.

As shown in FIG. 23, in another conventional crystal oscillator, metalland patterns (electrode patterns) 4 and a solder resist 8 are formed onan epoxy resin board 1, and a circuit component (electronic component) 2is mounted on the electrode patterns 4.

In detail, component electrodes 3 are formed on the electronic component2 at parts connected to the land patterns 4, and the componentelectrodes 3 and the land patterns 4 are fixed by mount solder 5.

[Related Art 1]

Related prior art includes Japanese Patent Application Laid-Open No.2004-200187 “Printed-Wiring Board” (Nikon Corporation) [Patent Document1], and Japanese Patent Application Laid-Open No. 2007-104005 “SurfaceMount Crystal Oscillator” (Nihon Dempa Kogyo Co., Ltd.) [Patent Document2].

[Related Art 2]

Related prior art includes Japanese Patent Application Laid-Open No.H11-135674 “Semiconductor Device and Manufacture thereof” (NEC Kansai,Ltd.) [Patent Document 3], Japanese Patent Application Laid-Open No.2000-332396 “Mounting Structure of Electronic Components” (Alps ElectricCo., Ltd.) [Patent Document 4], and Japanese Patent ApplicationLaid-Open No. 2008-238253 “Pb-free Soldering Material, and ManufacturingMethod of Semiconductor Mounted Structure using the same” (Hitachi,Ltd.) [Patent Document 5].

[Related Art 3]

Related prior art includes Japanese Patent Application Laid-Open No.H07-231237 “Multiple Mode Crystal Vibrator and Crystal Vibrator” (NihonDempa Kogyo Co., Ltd.) [Patent Document 6], Japanese Patent ApplicationLaid-Open No. H10-051263 “Crystal Vibrator” (River Eletec Corporation)[Patent Document 7], and Japanese Patent Application Laid-Open No.2003-037441 “Piezoelectric Device and Electronic Equipment” (Seiko EpsonCorp.) [Patent Document 8].

[Related Art 4]

Related prior art includes Japanese Patent Application Laid-Open No.2005-203525 “Power Semiconductor Device and Method of ManufacturingMetal Base Plate” (Mitsubishi Electric Corporation) [Patent Document 9],Japanese Patent Application Laid-Open No. 2007-089003 “PiezoelectricComponent” (TDK Corporation) [Patent Document 10], and Japanese PatentApplication Laid-Open No. 2010-087145 “Electronic Component MountingSubstrate” (FDK Corporation) [Patent Document 11].

Patent Document 1 discloses that a columnar projection is provided at anelectrode land where a solder ball bump is joined, and stress in atraverse direction is absorbed not only by an interface between thesolder ball bump and the electrode land but also by a side surface ofthe projection.

Patent Document 2 discloses that, in a surface mount oscillator in whicha crystal resonator and a mount substrate are joined, a projection isformed at connection terminals of the mount substrate in the case ofjoining the connection terminals of the mount substrate and resonatorterminals of the crystal resonator by solder.

Patent Document 3 discloses a semiconductor device in which asemiconductor pellet having fine-pitch bump electrodes can be connectedto a wiring board by forming a wide solder feeder on a fine conductivepattern.

Patent Document 4 discloses an electronic component mounting structurein which an insulation layer for coating an adhesive for temporarilyfixing electronic components is formed in regions for mounting theelectronic components so as to be thicker than a circuit pattern, sothat a predetermined gap is formed between bottom faces of theelectronic components mounted on the insulation layer and the circuitpattern.

Patent Document 5 discloses that a solder paste in which a Sn—Zn solderpowder and a Sn powder or Zn powder having a higher melting point thanthe Sn—Zn solder powder are mixed is used as a soldering material, tosuppress component inclination and secure soldered part thickness whenmounting low heat-resistant leadless components.

Patent Document 6 discloses a structure in which a crystal chip is fixedto two support sections using a conductive adhesive on a substrate tosupply a voltage from the support sections to the crystal chip, and acommon lead electrode formed on a side of the crystal chip not fixed tothe support sections is connected to a shield electrode formed on thesubstrate by wire bonding.

That is, a voltage is supplied from the two support sections on thesubstrate side to the crystal chip, and the common lead electrode on theopposite side of the crystal chip is connected to a ground level by wirebonding.

Patent Document 7 discloses that, in a crystal vibrator havinghorizontally arranged crystal vibrator bars, each crystal vibrator baris supported only at one end while the other end is kept free, therebyeliminating stress on the crystal vibrator bars.

Patent Document 8 discloses a structure in which an IC chip is mountedin a package and an electrode on an upper surface of the IC chip and anelectrode on a second layer are connected by a bonding wire.

Patent Document 9 discloses that, in a metal base plate, a low linearexpansion material having an expansion coefficient equivalent or closeto that of an insulating substrate is arranged at least at areascorresponding to four corners of the insulating substrate, to relaxshearing stress by heat cycle and suppress a solder crack in a solderjoining part between the insulating substrate and the metal base plate.

Patent Document 10 discloses that a piezoelectric unit formed bylaminating a base substrate, a piezoelectric substrate, and a top platein sequence and a printed board in which the piezoelectric unit ismounted by soldering satisfy specific conditional expressions regardinglinear expansion coefficients and also Vickers hardness and maximumdistortion of the base substrate are specified to thereby suppress asolder crack.

Patent Document 11 discloses that, by providing a ceramic sheet (strainsuppressing body) on a top surface or internal surface of a printedwiring board facing an electronic component, a difference in expansionbetween the electronic component and the printed wiring board due to atemperature change near the electronic component can be reduced,resulting in a reduction in stress applied to a fillet of solder.

-   [Patent Document 1] Japanese Patent Application Laid-Open No.    2004-200187-   [Patent Document 2] Japanese Patent Application Laid-Open No.    2007-104005-   [Patent Document 3] Japanese Patent Application Laid-Open No.    H11-135674-   [Patent Document 4] Japanese Patent Application Laid-Open No.    2000-332396-   [Patent Document 5] Japanese Patent Application Laid-Open No.    2008-238253-   [Patent Document 6] Japanese Patent Application Laid-Open No.    H07-231237-   [Patent Document 7] Japanese Patent Application Laid-Open No.    H10-051263-   [Patent Document 8] Japanese Patent Application Laid-Open No.    2003-037441-   [Patent Document 9] Japanese Patent Application Laid-Open No.    2005-203525-   [Patent Document 10] Japanese Patent Application Laid-Open No.    2007-089003-   [Patent Document 11] Japanese Patent Application Laid-Open No.    2010-087145

However, the above-mentioned conventional oscillator has a problem that,due to a difference in thermal expansion coefficient between theelectronic component (circuit component) using ceramic or the like andthe glass epoxy resin circuit board, strain concentrates on the mountsolder in a use environment where a heat cycle occurs, causing a crackin the solder.

It is commonly known that a solder crack is more likely to occur inlarge components than in small components.

However, certain circuit components cannot be reduced in size because oftheir performance or constants, and so there are many cases where largecircuit components need to be used.

Especially in an oven controlled crystal oscillator (OCXO), in a useenvironment where power on/off is repeated, a temperature change from anambient temperature to an oven control temperature (e.g. 85° C.) isadded at each instance of power on/off, which induces a crack in solder.Thus, there is a problem with long-term reliability.

Note, Patent Document 1 discloses that an electrode land provided with aprojection and an electrode facing the electrode land are joined by asolder ball bump, where the electrode land and the facing electrode arenot in contact. Though a force in a traverse direction is addressed,solder strain due to a difference in thermal expansion coefficientbetween the electrode land and the facing electrode is not taken intoconsideration.

Patent Document 2 discloses that connection terminals provided with aprojection are connected to resonator terminals by solder. Here, theresonator terminals and the connection terminals are made of the sametungsten, and therefore solder strain due to a difference in thermalexpansion coefficient between both terminals is not taken intoconsideration.

Patent Document 3 discloses that a solder feeder for easing solder feedis provided on a conductive pattern formed on a board, but does notdisclose a structure in which a thickness of a land pattern as anelectrode is exploited to lift an electronic component with respect tothe land pattern so as to create, between the land pattern and acomponent electrode formed on the electronic component, a space in whichsolder can be easily filled.

Patent Document 4 discloses that an insulation layer having coatingzones for coating an adhesive for temporarily fixing electroniccomponents is formed to create a gap between a circuit pattern and theelectronic components. Here, the dedicated insulation layer needs to beformed in order to lift the electronic components. Thus, Patent Document4 fails to disclose a structure of easily lifting the electroniccomponents by exploiting a normal circuit board manufacturing process.

Patent Document 5 discloses that a metallic spacer is formed on a pad ona mount substrate and a semiconductor element is mounted and soldered ata gap portion, but does not disclose a structure of increasing theamount of solder in soldering between an electrode pattern on thesubstrate and a component electrode of the electronic component to forma fillet, thereby strengthening adhesion.

Patent Document 6 discloses that a crystal chip is fixed to two supportsections on a substrate, and so does not address substrate expansion andcontraction caused by a temperature change.

Patent Document 7 merely discloses a structure of supporting eachcrystal vibrator bar only at one end. Patent Document 8 merely disclosesa structure of connecting an IC chip fixed in a package and an electrodeon a second layer by a bonding wire.

Patent Documents 9 to 11 disclose techniques for suppressing a soldercrack. However, these techniques require complex conditions andstructures, and are unable to suppress a solder crack caused by atemperature change by a simple structure at low cost.

SUMMARY OF THE INVENTION

The present invention was conceived in view of the above-mentionedcircumstances, and has an object of providing an oscillator that cansuppress a solder crack caused by a temperature change by a simplestructure at low cost and improve heat cycle resistance performance.

To solve the problems of the prior art stated above, the presentinvention is an oscillator (an oscillator according to a first group)including an epoxy resin board and a circuit component mounted on theboard, the oscillator comprising: two-terminal electrode patterns formedon the board and solder-connected to terminal electrodes of the circuitcomponent; a projection formed on each of the electrode patterns at apart of contact with a corresponding terminal electrode; and solderapplied onto the electrode pattern, the solder being filled in a spacebetween the electrode pattern and the terminal electrode and, as aresult of reflow after the circuit component is mounted, forming afillet between the electrode pattern and a side surface of the terminalelectrode. This has an advantageous effect of strengthening adhesion bythick solder formation, suppressing a solder crack caused by atemperature change by a simple structure at low cost, and improving heatcycle resistance performance.

The present invention is the oscillator according to the first groupwherein the projection is formed on the electrode pattern on a sidecloser to the other electrode pattern facing the electrode pattern.

The present invention is the oscillator according to the first groupwherein the solder forms the fillet in a space on the electrode patternwhere the projection is not formed.

The present invention is the oscillator according to the first groupwherein a plurality of projections are provided on each of the electrodepatterns.

The present invention is the oscillator according to the first groupwherein the projection has a height of 10 μm to 100 μm.

The present invention is the oscillator according to the first groupwherein the projection has a height of 20 μm to 50 μm.

The present invention is the oscillator according to the first groupwherein the two-terminal electrode patterns are arranged so that adirection in which the electrode patterns face each other matches adirection in which the board has a smallest linear expansioncoefficient. This has an advantageous effect of suppressing a soldercrack caused by a temperature change by a simple structure at low costand improving heat cycle resistance performance.

The present invention is the oscillator according to the first groupthat is applied to an oven controlled crystal oscillator.

The present invention is an oscillator (a first oscillator according toa second group) including an epoxy resin board and an electroniccomponent mounted on the board, the oscillator comprising: an electrodeland pattern formed on the board; a dummy land pattern formed on theboard where the electronic component is mounted; a solder resist formedso as to cover the dummy land pattern; and mount solder forsolder-connecting the electrode land pattern and a component electrodeformed at an end of the electronic component, in a state where theelectronic component is lifted by the dummy land pattern and the solderresist. This has an advantageous effect of strengthening adhesion bythick solder formation, suppressing a solder crack caused by atemperature change by a simple structure at low cost, and improving heatcycle resistance performance.

The present invention is the first oscillator according to the secondgroup wherein the solder resist is formed in two layers.

The present invention is a manufacturing method of an oscillator (amanufacturing method of the first oscillator according to the secondgroup) including an epoxy resin board and an electronic componentmounted on the board, the manufacturing method comprising: forming anelectrode land pattern on the board and a dummy land pattern on theboard where the electronic component is to be mounted; forming a solderresist so as to cover the dummy land pattern; applying solder onto theelectrode land pattern; mounting the electronic component on the solderresist; and solder-connecting the electrode land pattern and a componentelectrode formed at an end of the electronic component by reflow, in astate where the electronic component is lifted by the dummy land patternand the solder resist.

The present invention is the manufacturing method of the firstoscillator according to the second group wherein the solder resist isformed in two layers.

The present invention is an oscillator (a second oscillator according tothe second group) including an epoxy resin board and an electroniccomponent mounted on the board, the oscillator comprising: an electrodeland pattern formed on the board; a dummy land pattern formed on theboard where the electronic component is mounted; a solder resist formedso as to cover the dummy land pattern; a silk print layer formed so asto cover the solder resist; and mount solder for solder-connecting theelectrode land pattern and a component electrode formed at an end of theelectronic component, in a state where the electronic component islifted by the dummy land pattern, the solder resist, and the silk printlayer. This has an advantageous effect of strengthening adhesion bythick solder formation, suppressing a solder crack caused by atemperature change by a simple structure at low cost, and improving heatcycle resistance performance.

The present invention is a manufacturing method of an oscillator (amanufacturing method of the second oscillator according to the secondgroup) including an epoxy resin board and an electronic componentmounted on the board, the manufacturing method comprising: forming anelectrode land pattern on the board and a dummy land pattern on theboard where the electronic component is to be mounted; forming a solderresist so as to cover the dummy land pattern; forming a silk print layerso as to cover the solder resist; applying solder onto the electrodeland pattern; mounting the electronic component on the silk print layer;and solder-connecting the electrode land pattern and a componentelectrode formed at an end of the electronic component by reflow, in astate where the electronic component is lifted by the dummy landpattern, the solder resist, and the silk print layer.

The present invention is an oscillator (a third oscillator according tothe second group) including an epoxy resin board and an electroniccomponent mounted on the board, the oscillator comprising: an electrodeland pattern formed on the board; a solder resist formed so as topartially cover the electrode land pattern on a side closer to a centerof the electronic component; and mount solder for solder-connecting theelectrode land pattern and a component electrode formed at an end of theelectronic component, in a state where the electronic component islifted by the electrode land pattern and the solder resist. This has anadvantageous effect of strengthening adhesion by thick solder formation,suppressing a solder crack caused by a temperature change by a simplestructure at low cost, and improving heat cycle resistance performance.

The present invention is a manufacturing method of an oscillator (amanufacturing method of the third oscillator according to the secondgroup) including an epoxy resin board and an electronic componentmounted on the board, the manufacturing method comprising: forming anelectrode land pattern on the board; forming a solder resist so as topartially cover the electrode land pattern on a side closer to a centerof the electronic component; applying solder onto the electrode landpattern; mounting the electronic component on the solder resist; andsolder-connecting the electrode land pattern and a component electrodeformed at an end of the electronic component by reflow, in a state wherethe electronic component is lifted by the electrode land pattern and thesolder resist.

The present invention is the oscillator according to the second groupthat is applied to an oven controlled crystal oscillator.

The present invention is an oscillator (an oscillator according to athird group) in which an electronic component having a plurality ofterminal electrodes is mounted on a board, wherein pattern wirescorresponding to the plurality of terminal electrodes are formed on theboard, wherein a specific terminal electrode from among the plurality ofterminal electrodes is connected to a corresponding pattern wire bysolder, and wherein a terminal electrode other than the specificterminal electrode from among the plurality of terminal electrodes isconnected to a corresponding pattern wire by a bonding wire. This has anadvantageous effect of relaxing stress on solder caused by a temperaturechange through relaxation of thermal stress between an electroniccomponent and a board caused by a temperature change, suppressing asolder crack, and improving heat cycle resistance performance.

The present invention is the oscillator according to the third groupwherein the terminal electrode is formed on both upper and lowersurfaces of the electronic component, and wherein the bonding wire isconnected to a surface of the terminal electrode opposite to a surfacethat is connected to the pattern wire by the solder.

The present invention is the oscillator according to the third groupwherein an adhesive is provided between the board and a surface of theterminal electrode connected by the bonding wire, the surface of theterminal electrode facing the board.

The present invention is the oscillator according to the third groupwherein a pattern wire is provided between the board and a surface ofthe terminal electrode connected by the bonding wire, the surface of theterminal electrode facing the board.

The present invention is the oscillator according to the third groupwherein an electric wire material is used instead of the bonding wire.

The present invention is the oscillator according to the third groupthat is applied to an oven controlled crystal oscillator.

The present invention is an oscillator (a first oscillator according toa fourth group) including an epoxy resin board and a circuit componentmounted on the board, wherein two-terminal electrode patterns are formedon the board and connected to terminal electrodes of the circuitcomponent by solder, and wherein the two-terminal electrode patterns arearranged so that a direction in which the electrode patterns face eachother matches a direction in which the board has a smallest linearexpansion coefficient. This has an advantageous effect of suppressing asolder crack caused by a temperature change by a simple structure at lowcost and improving heat cycle resistance performance.

The present invention is an oscillator (a second oscillator according tothe fourth group) including an epoxy resin board and a circuit componentmounted on the board, wherein four-terminal electrode patterns areformed on the board and connected to terminal electrodes of the circuitcomponent by solder, and wherein the four-terminal electrode patternsare arranged so that a direction in which each pair of electrodepatterns formed at positions corresponding to corners on the same longerside of the circuit component face each other matches a direction inwhich the board has a smallest linear expansion coefficient. This has anadvantageous effect of suppressing a solder crack caused by atemperature change by a simple structure at low cost and improving heatcycle resistance performance.

The present invention is the oscillator according to the fourth groupwherein the circuit component is made of ceramic.

The present invention is the oscillator according to the fourth groupwherein a projection is provided on each of the electrode patterns at apart of contact with a corresponding terminal electrode, and the solderforms a fillet in a space created between the terminal electrode and theelectrode pattern. This has an advantageous effect of enhancing solderstrength, suppressing a solder crack caused by a temperature change by asimple structure at low cost, and improving heat cycle resistanceperformance.

The present invention is the oscillator according to the fourth groupthat is applied to an oven controlled crystal oscillator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an oscillator according to a first group.

FIG. 2 is a cross-section view of the oscillator according to the firstgroup.

FIG. 3 is an enlarged view of a connection part (solder part) between anelectrode pattern and a terminal electrode according to the first group.

FIG. 4 is a view showing a projection shape in a first example accordingto the first group.

FIG. 5 is a view showing a projection shape in a second exampleaccording to the first group.

FIG. 6 is a view showing a projection shape in a third example accordingto the first group.

FIG. 7 is a view showing a projection shape in a fourth exampleaccording to the first group.

FIG. 8 is a plan view of a first oscillator according to a second group.

FIG. 9A is a cross-section view as a first step of the first oscillatoraccording to the second group, and FIG. 9B is a cross-section view as asecond step of the first oscillator according to the second group.

FIG. 10 is a cross-section view of the first oscillator according to thesecond group.

FIG. 11A is a cross-section view as a first step showing an applicationexample of the first oscillator according to the second group, and FIG.11B is a cross section view as a second step showing an applicationexample of the first oscillator according to the second group.

FIG. 12 is a cross-section view of a second oscillator according to thesecond group.

FIG. 13A is a cross-section view as a first step of a third oscillatoraccording to the second group, FIG. 13B is a cross-section view as asecond step of a third oscillator according to the second group, andFIG. 13C is a cross-section view as a third step of a third oscillatoraccording to the second group.

FIG. 14A is a plan view of a first crystal oscillator according to athird group, and FIG. 14B is a section view of the first crystaloscillator according to the third group.

FIG. 15 is a cross-section view of a second crystal oscillator accordingto the third group.

FIG. 16 is a cross-section view of a third crystal oscillator accordingto the third group.

FIG. 17 is a schematic view showing two-terminal electrode patterns on aboard of an oscillator according to a fourth group.

FIG. 18 is a plan view of the oscillator according to the fourth group.

FIG. 19 is a cross-section view of the oscillator according to thefourth group.

FIG. 20 is a schematic view showing four-terminal electrode patternsaccording to the fourth group.

FIG. 21 is a cross-section view of another oscillator according to thefourth group.

FIG. 22A is a plan view of a conventional crystal oscillator, and FIG.22B is a cross-section view of the conventional crystal oscillator.

FIG. 23 is a cross-section view of another conventional crystaloscillator.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1: board    -   2: electronic component    -   3: terminal electrode    -   4: electrode pattern    -   5: solder    -   6: projection (protrusion)    -   11: board    -   12: electronic component    -   13: component electrode    -   14: land pattern    -   15: mount solder    -   17: dummy land pattern    -   18, 18 a, 18 b, 18 c: solder resist    -   19: silk print layer    -   21: board    -   22: electronic component    -   23, 23 a, 23 b: terminal electrode    -   24, 24 a, 24 b, 24 c: pattern wire    -   25: solder    -   26: bonding wire    -   27: adhesive    -   31: board    -   32: electronic component    -   33: terminal electrode    -   34: electrode pattern    -   35: solder

DESCRIPTION OF PREFERRED EMBODIMENT

The following describes embodiments of the present invention withreference to drawings.

In detail, the embodiments of the present invention are classified intofirst to fourth groups.

[Overview of Embodiment According to First Group]

In an oscillator according to an embodiment of the present invention (anoscillator according to the first group), a projection is formed on anelectrode pattern formed on a circuit board of a glass epoxy resin, at apart of contact with each terminal electrode of a circuit component.Solder is filled in a space created between the terminal electrode andthe electrode pattern by the projection, and also forms a fillet on aside surface of the terminal electrode. This strengthens solderadhesion, relaxes strain on mount solder caused by a temperature changedue to a difference in thermal expansion coefficient between the circuitcomponent and the glass epoxy resin material, and improves heat cycleresistance performance.

[Oscillator According to First Group: FIGS. 1 and 2]

The oscillator according to the embodiment of the present invention (theoscillator according to the first group) is described below, withreference to FIGS. 1 and 2. FIG. 1 is a plan view of the oscillatoraccording to the first group, and FIG. 2 is a section view of theoscillator according to the first group.

As shown in FIGS. 1 and 2, in the oscillator according to the firstgroup, metal electrode patterns 4 are formed on an epoxy resin board 1,and a circuit component (electronic component) 2 is mounted on theelectrode patterns 4.

In detail, terminal electrodes 3 are formed on the electronic component2 at parts connected to the electrode patterns 4, and the terminalelectrodes 3 and the electrode patterns 4 are fixed by solder 5.

For example, the electronic component 2 is made of ceramic or the like.

As the epoxy resin material of the board 1, CEM-3 (Composite EpoxyMaterial 3), FR-4 (Flame Retardant Type 4), or the like is employed.

CEM-3 is a glass epoxy board based on a plate composed of a mixture offiberglass and an epoxy resin.

FR-4 is a glass epoxy board based on a plate composed of wovenfiberglass cloth impregnated with an epoxy resin.

[Partial Enlargement: FIG. 3]

The part where each electrode pattern 4 is connected to thecorresponding terminal electrode 3 by the solder 5 is described below,with reference to FIG. 3. FIG. 3 is an enlarged view of the connectionpart (solder part) between the electrode pattern and the terminalelectrode.

As shown in FIG. 3, a projection (protrusion) 6 is formed on theelectrode pattern 4 on the board 1, at a part of contact with theterminal electrode 3 of the electronic component 2.

The solder 5 is applied onto the electrode pattern 4, and also theelectronic component 2 is mounted.

In detail, a tip of the projection 6 contacts the terminal electrode 3,and the solder 5 is filled in a space created between the electrodepattern 4 and the terminal electrode 3. After reflow, the solder 5 formsa fillet on a side surface of the terminal electrode 3.

The projection 6 has a height of about 10 μm to 100 μm, and optimallyhas a height of about 20 μm to 50 μm, though this may differ dependingon an oscillator product.

For example, the projection 6 is produced by depositing a plated layeron the electrode pattern 4 and performing masking so that a specificportion remains.

The projection 6 is formed on the electrode pattern 4 on a side closerto the other electrode pattern 4, and the solder 5 forms theabove-mentioned fillet in a space where the projection 6 is not formed.

In this oscillator, the solder 5 for bonding the electrode pattern 4 andthe terminal electrode 3 is increased in amount (i.e. increased inthickness), as compared with the conventional structure without theprojection 6. Thus, the adhesion between the electrode pattern 4 and theterminal electrode 3 can be strengthened.

This has an advantageous effect of relaxing strain on mount soldercaused by a temperature change and improving heat cycle resistanceperformance, even when the board 1 on which the electrode pattern 4 isformed and the electronic component 2 on which the terminal electrode 3is formed differ in thermal expansion coefficient.

A shape of the projection 6 formed on the electrode pattern 4 isdescribed below using four patterns as examples, with reference to FIGS.4 to 7. FIG. 4 is a view showing a projection shape in a first exampleaccording to the first group. FIG. 5 is a view showing a projectionshape in a second example according to the first group. FIG. 6 is a viewshowing a projection shape in a third example according to the firstgroup. FIG. 7 is a view showing a projection shape in a fourth exampleaccording to the first group. In each of FIGS. 4 to 7, the upper view isa plan view, and the lower view is a section view.

[First Example According to First Group: FIG. 4]

As shown in FIG. 4, in the first example according to the first group,two cylindrical projections 6 are provided on the electrode pattern 4 onthe side closer to the other electrode pattern 4.

The fillet of the solder 5 is formed in a space on the electrode pattern4 where the projections 6 are not formed.

The cylindrical shape eases manufacturing because the projections 6 areformed by masking.

[Second Example According to First Group: FIG. 5]

As shown in FIG. 5, in the second example according to the first group,a rectangular prism projection 6 is provided on the electrode pattern 4on the side closer to the other electrode pattern 4.

The fillet of the solder 5 is formed in a space on the electrode pattern4 where the projection 6 is not formed, as in the first example.

Since the terminal electrode 3 and the projection 6 have a largercontact surface, the space in which the solder 5 is filled between theelectrode pattern 4 and the terminal electrode 3 is reduced, as comparedwith the first example. Though this causes a slight decrease in adhesionstrength, the electronic component 2 can be mounted more stably.

[Third Example According to First Group: FIG. 6]

As shown in FIG. 6, in the third example according to the first group,three cylindrical projections 6 are provided on the electrode pattern 4on the side closer to the other electrode pattern 4.

The fillet of the solder 5 is formed in a space on the electrode pattern4 where the projections 6 are not formed, as in the first example.

The cylindrical shape eases manufacturing because the projections 6 areformed by masking.

As in the second example, since the terminal electrode 3 and theprojections 6 have a larger contact surface, the space in which thesolder 5 is filled between the electrode pattern 4 and the terminalelectrode 3 is reduced, as compared with the first example. Though thiscauses a slight decrease in adhesion strength, the electronic component2 can be mounted more stably.

[Fourth Example According to First Group: FIG. 7]

As shown in FIG. 7, in the fourth example according to the first group,two rectangular prism projections 6 are provided on the electrodepattern 4 on the side closer to the other electrode pattern 4.

The fillet of the solder 5 is formed in a space on the electrode pattern4 where the projections 6 are not formed, as in the first example.

[Embodiment of Application Example]

An application example of the above-mentioned oscillator is describedbelow.

In the application example, the two-terminal electrode patterns 4 onwhich the electronic component 2 is mounted are arranged so as to faceeach other in a direction same as a direction in which the glass epoxyresin board 1 has a smallest linear expansion coefficient.

In the case of a typical CEM-3 board as the board 1, the linearexpansion coefficient is 25 ppm/° C. in a longitudinal direction, 28ppm/° C. in a lateral direction, and 65 ppm/° C. in a thicknessdirection.

In the case of a typical FR-4 board, the linear expansion coefficient is13 ppm/° C. in the longitudinal direction, 16 ppm/° C. in the lateraldirection, and 60 ppm/° C. in the thickness direction.

Meanwhile, the linear expansion coefficient of ceramic (alumina) of theelectronic component 2 is, for example, about 7 ppm/° C.

Here, the long-scale direction of the board 1 is “longitudinaldirection” and the short-scale direction of the board 1 is “lateraldirection” in FIG. 1.

Typical FR-4 has the linear expansion coefficient of 13 ppm/° C. in thelongitudinal direction, which is smaller than the linear expansioncoefficient of 16 ppm/° C. in the lateral direction. On the other hand,the linear expansion coefficient of typical FR-4 in the thicknessdirection of the board 1 is 60 ppm/° C.

Therefore, the board 1 has the smallest linear expansion coefficient inthe longitudinal direction (long-scale direction).

Hence, the direction in which the electrode patterns 4 face each otheris set to match (in the same direction as) the longitudinal direction(long-scale direction) with the smallest linear expansion coefficient,as shown in FIG. 1.

That is, the two-terminal electrode patterns 4 on which the electroniccomponent 2 is mounted are arranged so as to face each other in the samedirection as the longitudinal direction in which the board 1 has thesmallest linear expansion coefficient.

[Heat Cycle Resistance Performance]

The terminal electrode 3 formed on the electronic component 2 and theelectrode pattern 4 formed on the board 1 are especially influenced inthe longitudinal direction of the board 1 (the longer-scale direction ofthe board 1 in FIG. 1), by thermal expansion due to a difference inlinear expansion coefficient between the electronic component 2 ofceramic or the like and the epoxy resin board 1.

This being so, when the linear expansion coefficient of the board 1 inthe longitudinal direction in which the terminal electrode 3 and theelectrode pattern 4 tend to be influenced by thermal expansion is small,the influence can be minimized. This has an advantageous effect ofrelaxing strain on the solder 5, suppressing a crack in the solder 5,and improving heat cycle resistance performance.

[Advantageous Effect of Embodiment According to First Group]

In the oscillator according to the first group, the projection 6 isformed on the electrode pattern 4 at the part connected to the terminalelectrode 3 to create a space between the terminal electrode 3 and theelectrode pattern 4, and the fillet of the solder 5 is formed in thespace. This has an advantageous effect of enhancing the adhesionstrength of the solder 5, suppressing a crack in the solder 5, andimproving heat cycle resistance performance.

In the oscillator of the application example according to the firstgroup, based on the structure of the above-mentioned oscillator, thedirection in which the two-terminal electrode patterns 4 formed on theepoxy resin board 1 face each other is set to match the direction inwhich the linear expansion coefficient of the board 1 is small. This hasan advantageous effect of relaxing strain on the solder 5 applied ontothe electrode pattern 4 due to a temperature change, suppressing a crackin the solder 5, and improving heat cycle resistance performance.

The oscillator according to the first group and the oscillator of theapplication example according to the first group can each be effectivelyapplied to an oven controlled crystal oscillator.

[Overview of Embodiment According to Second Group]

In an oscillator according to an embodiment of the present invention (anoscillator according to the second group), a lifter for lifting anelectronic component is formed on a circuit board of a glass epoxyresin. In a part of contact between an electrode land pattern formed onthe board and a component electrode of the electronic component, mountsolder is filled in a space created between the component electrode andthe land pattern, and also forms a fillet on a side surface of thecomponent electrode. This strengthens mount solder adhesion, relaxesstrain on mount solder caused by a temperature change due to adifference in thermal expansion coefficient between the electroniccomponent and the glass epoxy resin material, and improves heat cycleresistance performance.

[First Oscillator According to Second Group: FIGS. 8, 9, and 10]

An oscillator according to a first embodiment of the present invention(a first oscillator according to the second group) is described below,with reference to FIGS. 8, 9, and 10. FIG. 8 is a plan view of the firstoscillator according to the second group, FIG. 9 is a manufacturesection view of the first oscillator according to the second group, andFIG. 10 is a section view of the first oscillator according to thesecond group.

As shown in FIGS. 8 and 10, in the first oscillator according to thesecond group, metal land patterns (electrode patterns) 14 and dummy landpattern 17 are formed on an epoxy resin board 11, a solder resist 18 ais formed on the board 11 and the dummy land pattern 17, and a circuitcomponent (electronic component) 12 is mounted on the land patterns 14.

For example, the electronic component 12 is made of ceramic or the like,and the solder resist 18 a is made of a thermosetting epoxy resin or thelike.

In detail, component electrodes 13 are formed on the electroniccomponent 12, at parts connected to the land patterns 14. That is, thecomponent electrodes 13 are formed at ends of the electronic component12.

The electronic component 12 is lifted from the land patterns 14 by aheight corresponding to a thickness of the solder resist 18 a at itscenter bottom part, by a lifter formed by laminating the dummy landpattern 17 and the solder resist 18 a. In other words, the dummy landpattern 17 and the solder resist 18 a constitute the lifter for liftingthe electronic component 12.

The component electrodes 13 and the land patterns 14 are fixed by mountsolder 15.

Here, the solder resist 18 a is formed on the dummy land pattern 17, butis not formed on the land patterns 14 serving as electrodes.

The dummy land pattern 17 and the land patterns 14 are manufactured inthe same process, and so have the same thickness. Hence, the electroniccomponent 12 is lifted by the height corresponding to the thickness ofthe solder resist 18 a formed on the dummy land pattern 17.

Meanwhile, on each land pattern 14, the corresponding componentelectrode 13 formed on the electronic component 12 is present.Accordingly, a gap between the component electrode 13 and the landpattern 14 is smaller than the lifting height.

The mount solder 15 is filled in the gap between the land pattern 14 andthe component electrode 13, and also forms a fillet between the landpattern 14 and a side surface of the component electrode 13.

As the epoxy resin material of the board 11, CEM-3 (Composite EpoxyMaterial 3), FR-4 (Flame Retardant Type 4), or the like is employed.

CEM-3 is a glass epoxy board based on a plate composed of a mixture offiberglass and an epoxy resin.

FR-4 is a glass epoxy board based on a plate composed of wovenfiberglass cloth impregnated with an epoxy resin.

A metal layer of the land patterns 14 and the dummy land pattern 17 istypically formed with a thickness of about 10 μm to 50 μm. In FIG. 8,the thickness is about 45 μm to 50 μm, as an example.

The solder resist 18 a is about 10 μm in thickness.

The solder resist 18 a is shown in the section views of FIGS. 9 and 10,but is not shown in FIG. 8 for the sake of clarity.

[Manufacturing Method of First Oscillator According to Second Group:FIG. 9]

A manufacturing method of the first oscillator according to the secondgroup is described below, with reference to FIGS. 9 and 10. FIG. 9 is amanufacture section view of the first oscillator according to the secondgroup.

The first oscillator according to the second group is manufactured asfollows. As shown in FIG. 9A, the land patterns 14 serving as electrodesand the dummy land pattern 17 are formed by a metal film, on the epoxyresin board 11.

The dummy land pattern 17 is situated at the center of the positionwhere the electronic component 12 is mounted, while the land patterns 14are situated at the positions where the component electrodes 13 attachedto the electronic component 12 are connected.

Next, as shown in FIG. 9B, the solder resist 18 a is formed at necessaryparts on the board 11 so as to cover the dummy land pattern 17.

Here, the solder resist 18 a does not cover the electrode land patterns14.

The mount solder 15 is then applied onto the land patterns 14, and theelectronic component 12 is mounted on the laminate structure of thedummy land pattern 17 and the solder resist 18 a so that each componentelectrode 13 is positioned on the corresponding land pattern 14.

In detail, since the electronic component 12 is lifted by the thicknessof the dummy land pattern 17 and the solder resist 18 a, the mountsolder 15 is filled in a space (gap) created between the componentelectrode 13 and the land pattern 14. After reflow, the fillet of themount solder 15 is formed on the side surface of the component electrode13.

In the first oscillator according to the second group, the mount solder15 for bonding the land pattern 14 and the component electrode 13 isincreased in amount (i.e. increased in thickness), as compared with theconventional structure shown in FIG. 23. Thus, the adhesion between theland pattern 14 and the component electrode 13 can be strengthened.

This has an advantageous effect of relaxing strain on the mount solder15 caused by a temperature change and improving heat cycle resistanceperformance, even when the board 11 on which the land pattern 14 isformed and the electronic component 12 on which the component electrode13 is formed differ in thermal expansion coefficient.

[Application Example of First Oscillator According to Second Group: FIG.11]

An application example of the first oscillator according to the secondgroup is described below, with reference to FIG. 11. FIG. 11 is amanufacture section view showing the application example of the firstoscillator according to the second group.

In the application example of the first oscillator shown in FIG. 11, thelifting height of the electronic component 12 is increased as comparedwith that in FIG. 10, by forming the solder resist in two layers.

Solder resists 18 a and 18 b are each about 10 μm in thickness.Accordingly, in the case of forming two solder resist layers, the solderresist thickness is about 20 μm. As a result, the electronic component12 is lifted higher than in the first oscillator, by about 10 μm.

In detail, as shown in FIG. 11A, the land patterns 14 and 17 are formedon the board 11, the solder resist 18 a is formed on the dummy landpattern 17 and the board 11, and the solder resist 18 b is formed on thesolder resist 18 a.

The mount solder 15 is then applied onto the land patterns 14, and theelectronic component 12 is mounted on the solder resist 18 b in a stateof being lifted from the land patterns 14. The mount solder 15 is filledin a space (gap) created between the corresponding component electrode13 and land pattern 14 and, after reflow, forms a fillet on the sidesurface of the component electrode 13.

In the application example of the first oscillator according to thesecond group, the gap between the land pattern 14 and the componentelectrode 13 is increased and so the amount of the mount solder 15filled is increased, as compared with the first oscillator in FIG. 10.Thus, the adhesion between the land pattern 14 and the componentelectrode 13 can be strengthened. This has an advantageous effect ofrelaxing strain on the mount solder 15 caused by a temperature changeand improving heat cycle resistance performance, even when the board 11and the electronic component 12 differ in thermal expansion coefficient.

[Second Oscillator According to Second Group: FIG. 12]

An oscillator according to a second embodiment of the present invention(a second oscillator according to the second group) is described below,with reference to FIG. 12. FIG. 12 is a section view of the secondoscillator according to the second group.

As shown in FIG. 12, in the second oscillator according to the secondgroup, a silk print layer 19 is formed on the upper surface of thesolder resist 18 a in the first oscillator in FIG. 10, and theelectronic component 12 is mounted on the silk print layer 19.

The silk print layer 19 is an insulation ink layer produced bysilk-screen printing (silk printing).

Hence, the electronic component 12 has the component electrodes 13lifted from the land patterns 14, by the dummy land pattern 17, thesolder resist 18 a, and the silk print layer 19. In other words, thedummy land pattern 17, the solder resist 18 a, and the silk print layer19 constitute the lifter.

Here, the silk print layer 19 is about 10 μm in thickness.

Since resist formation and silk printing are typically performed in anoscillator manufacturing process, silk printing is employed here. Thiscontributes to a more efficient manufacturing process than in theapplication example of the first oscillator according to the secondgroup where the two layers of the solder resists 18 a and 18 b areformed.

In the second oscillator according to the second group, the solderresist 18 a and the silk print layer 19 are about 20 μm in totalthickness, which is equivalent to the thickness in the applicationexample of the first oscillator (the solder resist 18 a of about 10 μmin thickness+the solder resist 18 b of about 10 μm in thickness=about 20μm). Therefore, the same effect of lifting the electronic component 12can be attained.

In the second oscillator according to the second group, by forming thesolder resist 18 a and the silk print layer 19 on the dummy land pattern17, the space created between the land pattern 14 and the componentelectrode 13 is increased and so the amount of the mount solder 15filled in the space is increased. Thus, the adhesion between the landpattern 14 and the component electrode 13 can be strengthened. This hasan advantageous effect of relaxing strain on the mount solder 15 causedby a temperature change and improving heat cycle resistance performance,even when the board 11 and the electronic component 12 differ in thermalexpansion coefficient.

[Third Oscillator According to Second Group: FIG. 13]

An oscillator according to a third embodiment of the present invention(a third oscillator according to the second group) is described below,with reference to FIG. 13. FIG. 13 is a manufacture section view of thethird oscillator according to the second group.

In the third oscillator according to the second group, the land patterns14 are formed on the board 11 as shown in FIG. 13A, and a solder resist18 c is formed so as to partially cover each land pattern 14 as shown inFIG. 13B.

Here, the land patterns 14 are about 45 μm to 50 μm in thickness, andthe solder resist 18 c is about 10 μm in thickness.

The part of each land pattern 14 on which the solder resist 18 c isformed is a part closer to the center of the electronic component 12mounted.

In FIG. 13, the solder resist 18 c is formed in an entire areaunderneath the electronic component 12, so as to partially cover theland patterns 14 facing each other.

Moreover, it is desirable that the solder resist 18 c supports only apart of the component electrode 13 on the board 11 side. If the solderresist 18 c occupies the area between the land pattern 14 and thecomponent electrode 13, the adhesion by the mount solder 15 is weakened.To prevent this, it is desirable to create a space between the componentelectrode 13 and the land pattern 14 to thereby achieve strong adhesionby the mount solder 15.

As shown in FIG. 13C, the mount solder 15 is then applied onto the landpatterns 14, and the electronic component 12 is mounted so that thecomponent electrodes 13 of the electronic component 12 are in contactwith the solder resist 18 c formed on the land patterns 14. The mountsolder 15 is filled in a space created between each component electrode13 and the corresponding land pattern 14 and, after reflow, forms afillet on the side surface of the component electrode 13.

In the third oscillator according to the second group, the electroniccomponent 12 is lifted by the solder resist 18 c formed so as topartially cover the land pattern 14 so that a space (gap) is createdbetween the component electrode 13 and the land pattern 14. The mountsolder 15 is filled in the space and also forms a fillet on the sidesurface of the component electrode 13. This has an advantageous effectof strengthening the adhesion of the mount solder 15.

In other words, the part of the land pattern 14 and the solder resist 18c formed on the part of the land pattern 14 constitute the lifter forlifting the electronic component 12.

This technique of the third oscillator according to the second group isapplicable to small components. The first and second oscillators are notsuitable for small components, because the lifter needs to be formedbetween the land patterns 14 serving as electrodes. On the other hand,the third oscillator can be applied to small components so long aspatterning is accurately performed.

[Advantageous Effect of Embodiment According to Second Group]

In the first oscillator according to the second group, a space iscreated between the land pattern 14 and the component electrode 13, sothat the mount solder 15 for bonding the land pattern 14 and thecomponent electrode 13 is increased in amount. Thus, the adhesionbetween the land pattern 14 and the component electrode 13 can bestrengthened. This has an advantageous effect of relaxing strain on themount solder 15 caused by a temperature change and improving heat cycleresistance performance, even when the board 11 on which the land pattern14 is formed and the electronic component 12 on which the componentelectrode 13 is formed differ in thermal expansion coefficient.

In the application example of the first oscillator according to thesecond group, by covering the dummy land pattern 17 with the two layersof the solder resists 18 a and 18 b, the space between the land pattern14 and the component electrode 13 is increased and so the amount of themount solder 15 filled in the space is increased. Thus, the adhesionbetween the land pattern 14 and the component electrode 13 can bestrengthened. This has an advantageous effect of relaxing strain on themount solder 15 caused by a temperature change and improving heat cycleresistance performance, even when the board 11 and the electroniccomponent 12 differ in thermal expansion coefficient.

In the second oscillator according to the second group, by forming thesolder resist 18 a and the silk print layer 19 on the dummy land pattern17, the space between the land pattern 14 and the component electrode 13is increased and so the amount of the mount solder 15 filled in thespace is increased. Thus, the adhesion between the land pattern 14 andthe component electrode 13 can be strengthened. This has an advantageouseffect of relaxing strain on the mount solder 15 caused by a temperaturechange and improving heat cycle resistance performance, even when theboard 11 and the electronic component 12 differ in thermal expansioncoefficient.

In the third oscillator according to the second group, the electroniccomponent 12 is lifted by the solder resist 18 c formed so as topartially cover the land pattern 14, to create a space between thecomponent electrode 13 and the land pattern 14. The mount solder 15 isfilled in the space, and also the fillet of the mount solder 15 isformed on the side surface of the component electrode 13. Thus, theadhesion of the mount solder 15 can be strengthened. This has anadvantageous effect of relaxing strain on the mount solder 15 caused bya temperature change and improving heat cycle resistance performance,even when the board 11 and the electronic component 12 differ in thermalexpansion coefficient.

The first to third oscillators according to the second group can each beeffectively applied to an oven controlled crystal oscillator.

[Overview of Embodiment According to Third Group]

In an oscillator according to an embodiment of the present invention (anoscillator according to the third group), an electronic component havingtwo terminal electrodes is mounted on a board of a glass epoxy resin.Pattern wires are formed on the board in correspondence with theterminal electrodes. One terminal electrode is connected to acorresponding pattern wire by solder, whereas the other terminalelectrode is connected to a corresponding pattern wire by a bondingwire. This relaxes stress on mount solder caused by a temperature changedue to a difference in linear expansion coefficient between the circuitcomponent and the glass epoxy resin material, and improves heat cycleresistance performance.

[First Crystal Oscillator According to Third Group: FIG. 14]

A crystal oscillator according to a first embodiment of the presentinvention (a first crystal oscillator according to the third group) isdescribed below, with reference to FIG. 14. FIG. 14A is a plan view ofthe first crystal oscillator according to the third group, and FIG. 14Bis a section view of the first crystal oscillator according to the thirdgroup.

As shown in FIG. 14, in the first crystal oscillator according to thethird group, two pattern wires 24 a and 24 b are formed on a circuitboard (board) 21 of a glass epoxy resin, and an electronic component 22provided with terminal electrodes 23 a and 23 b is mounted on the board21.

In detail, the pattern wire 24 a and the terminal electrode 23 a areconnected by solder 25, whereas the terminal electrode 23 b and thepattern wire 24 b are connected by a bonding wire 26.

CEM-3 (Composite Epoxy Material 3), FR-4 (Flame Retardant Type 4), orthe like is used as the material of the board 21.

CEM-3 is a glass epoxy board based on a plate composed of a mixture offiberglass and an epoxy resin.

FR-4 is a glass epoxy board based on a plate composed of wovenfiberglass cloth impregnated with an epoxy resin.

In the case of a typical CEM-3 board, the linear expansion coefficientis 25 ppm/° C. in a longitudinal direction, 28 ppm/° C. in a lateraldirection, and 65 ppm/° C. in a thickness direction.

In the case of a typical FR-4 board, the linear expansion coefficient is13 ppm/° C. in the longitudinal direction, 16 ppm/° C. in the lateraldirection, and 60 ppm/° C. in the thickness direction.

Meanwhile, the linear expansion coefficient of ceramic (alumina) of thecircuit component is, for example, about 7 ppm/° C.

For example, the electronic component 22 is a crystal resonator, a largeresistor, or the like.

The pattern wires 24 a and 24 b and the terminal electrodes 23 a and 23b are made of conductive metal.

Here, an electric wire material may be used instead of the bonding wire26.

[Manufacturing Method of First Crystal Oscillator According to ThirdGroup]

In a manufacturing method of the first crystal oscillator according tothe third group, the pattern wires 24 a and 24 b are formed on the glassepoxy resin board 21, the electronic component 22 having the terminalelectrodes 23 a and 23 b is mounted, the pattern wire 24 a and theterminal electrode 23 a are connected and bonded by the solder 25, andthe terminal electrode 23 b and the pattern wire 24 b are connected bythe bonding wire 26.

In particular, a part of a surface (upper surface) of the terminalelectrode 23 b opposite to a surface facing the board 21 is connected tothe pattern wire 24 b by the bonding wire 26. This is because theconnection by the bonding wire 26 can be easily made from the uppersurface.

[Second Crystal Oscillator According to Third Group: FIG. 15]

A crystal oscillator according to a second embodiment of the presentinvention (a second crystal oscillator according to the third group) isdescribed below, with reference to FIG. 15. FIG. 15 is a section view ofthe second crystal oscillator according to the third group.

As shown in FIG. 15, the second crystal oscillator according to thethird group is similar to the first crystal oscillator in FIG. 14, butdiffers in that an adhesive 27 is inserted between the board 21 and theterminal electrode 23 b on the board 21 side to bond the terminalelectrode 23 b and the board 21 by the adhesive 27.

The bonding by the adhesive 27 can prevent the electronic component 22from becoming unstable.

[Manufacturing Method of Second Crystal Oscillator According to ThirdGroup]

In a manufacturing method of the second crystal oscillator according tothe third group, the pattern wires 24 a and 24 b are formed on the glassepoxy resin board 21, the adhesive 27 is applied, the electroniccomponent 22 having the terminal electrodes 23 a and 23 b is mounted,the board 21 and the terminal electrode 23 b are bonded by the adhesive27, the pattern wire 24 a and the terminal electrode 23 a are connectedand bonded by the solder 25, and the terminal electrode 23 b and thepattern wire 24 b are connected by the bonding wire 26.

Here, the adhesive 27 may be inserted after the solder 25 is formed.

[Third Crystal Oscillator According to Third Group: FIG. 16]

A crystal oscillator according to a third embodiment of the presentinvention (a third crystal oscillator according to the third group) isdescribed below, with reference to FIG. 16. FIG. 16 is a section view ofthe third crystal oscillator according to the third group.

As shown in FIG. 16, the third crystal oscillator according to the thirdgroup is similar to the first crystal oscillator in FIG. 14 or thesecond crystal oscillator in FIG. 15, but differs in that a pattern wire24 c is formed between the board 21 and the terminal electrode 23 b onthe board 21 side to connect the terminal electrode 23 b and the board21 by the pattern wire 24 c.

The connection by the pattern wire 24 c can prevent the electroniccomponent 22 from becoming unstable.

Note, since the terminal electrode 23 b is electrically connected to thepattern wire 24 b by the bonding wire 26, the pattern wire 24 c ismerely used to fill up the gap between the terminal electrode 23 b andthe board 21 and does not provide electrical connection.

Moreover, while the terminal electrode 23 a and the pattern wire 24 aare bonded by the solder 25, the terminal electrode 23 b and the patternwire 24 c are not bonded by the solder 25 but are in a state where theterminal electrode 23 b is placed on the pattern wire 24 c.

[Manufacturing Method of Third Crystal Oscillator According to ThirdGroup]

In a manufacturing method of the third crystal oscillator according tothe third group, the pattern wires 24 a, 24 b, and 24 c are formed onthe glass epoxy resin board 21, the electronic component 22 having theterminal electrodes 23 a and 23 b is mounted, the pattern wire 24 c andthe terminal electrode 23 b are connected (in contact), the pattern wire24 a and the terminal electrode 23 a are connected and bonded by thesolder 25, and the terminal electrode 23 b and the pattern wire 24 b areconnected by the bonding wire 26.

[Advantageous Effect of Embodiment According to Third Group]

In the first crystal oscillator according to the third group, thepattern wires 24 a and 24 b are formed on the epoxy resin board 21, andthe electronic component 22 having the terminal electrodes 23 a and 23 bis mounted on the board 21, where the terminal electrode 23 a and thepattern wire 24 a are connected by the solder 25 whereas the terminalelectrode 23 b and the pattern wire 24 b are connected by the bondingwire 26. This has an advantageous effect of relaxing stress on thesolder 25 caused by a temperature change by relaxation of thermal stressbetween the electronic component 22 and the board 21 caused by atemperature change, suppressing a crack in the solder 25, and improvingheat cycle resistance performance.

In the second crystal oscillator according to the third group, theterminal electrode 23 b and the board 21 are bonded by the adhesive 27.This has an advantageous effect of stabilizing the electronic component22, in addition to the advantageous effect of the first crystaloscillator.

In the third crystal oscillator according to the third group, theterminal electrode 23 b and the board 21 are connected by the patternwire 24 c. This has an advantageous effect of stabilizing the electroniccomponent 22, in addition to the advantageous effect of the firstcrystal oscillator.

[Overview of Embodiment According to Fourth Group]

In an oscillator according to an embodiment of the present invention (anoscillator according to the fourth group), a direction in whichelectrode patterns formed on a circuit board of a glass epoxy resin andsoldered to a large circuit component mounted thereon face each other isset to match a direction in which the circuit board has a smallestlinear expansion coefficient. This relaxes stress on mount solder causedby a temperature change due to a difference in linear expansioncoefficient between the circuit component and the glass epoxy resinmaterial, and improves heat cycle resistance performance.

[Two-Terminal Electrode Patterns: FIG. 17]

The oscillator according to the embodiment of the present invention (theoscillator according to the fourth group) is described below, withreference to FIG. 17. FIG. 17 is a schematic view showing two-terminalelectrode patterns on a board in the oscillator according to the fourthgroup.

As shown in FIG. 17, in the oscillator according to the embodiment ofthe present invention (the oscillator according to the fourth group),two-terminal electrode patterns 34 are formed on a circuit board (board)31 of a glass epoxy resin.

CEM-3 (Composite Epoxy Material 3), FR-4 (Flame Retardant Type 4), orthe like is used as the material of the board 31.

CEM-3 is a glass epoxy board based on a plate composed of a mixture offiberglass and an epoxy resin.

FR-4 is a glass epoxy board based on a plate composed of wovenfiberglass cloth impregnated with an epoxy resin.

In the case of a typical CEM-3 board, the linear expansion coefficientis 25 ppm/° C. in a longitudinal direction, 28 ppm/° C. in a lateraldirection, and 65 ppm/° C. in a thickness direction.

In the case of a typical FR-4 board, the linear expansion coefficient is13 ppm/° C. in the longitudinal direction, 16 ppm/° C. in the lateraldirection, and 60 ppm/° C. in the thickness direction.

Meanwhile, the linear expansion coefficient of ceramic (alumina) of thecircuit component is, for example, about 7 ppm/° C.

Here, the long-scale direction of the board 31 is “longitudinaldirection” and the short-scale direction of the board 31 is “lateraldirection” in FIG. 17.

Typical FR-4 has the linear expansion coefficient of 13 ppm/° C. in thelongitudinal direction, which is smaller than the linear expansioncoefficient of 16 ppm/° C. in the lateral direction.

On the other hand, the linear expansion coefficient of typical FR-4 inthe thickness direction of the board 31 is 60 ppm/° C.

Therefore, the board 31 has the smallest linear expansion coefficient inthe longitudinal direction.

Hence, the direction in which the electrode patterns 34 face each otheris set to match (in the same direction as) the longitudinal directionwith the smallest linear expansion coefficient, as shown in FIG. 17.

The two-terminal electrode patterns 34 are electrode patterns on which alarge circuit component is mounted.

[Structure of Oscillator According to Fourth Group: FIGS. 18 and 19]

A structure of the oscillator according to the fourth group is describedbelow, with reference to FIGS. 18 and 19. FIG. 18 is a plan view of theoscillator according to the fourth group, and FIG. 19 is a section viewof the oscillator according to the fourth group.

As shown in FIGS. 18 and 19, in the oscillator according to the fourthgroup, the metal electrode patterns 34 are formed on the epoxy resinboard 31, and a circuit component (electronic component) 32 is mountedon the electrode patterns 34.

In detail, terminal electrodes 33 are formed on the electronic component32 at parts connected to the electrode patterns 34, and the terminalelectrodes 33 and the electrode patterns 34 are fixed by solder 35.

The two-terminal electrode patterns 34 on which the electronic component32 is mounted are arranged so as to face each other in the samedirection as the longitudinal direction in which the linear expansioncoefficient of the board 31 is smallest.

[Heat Cycle Resistance Performance]

The terminal electrode 33 formed on the electronic component 32 and theelectrode pattern 34 formed on the board 31 are especially influenced inthe longitudinal direction of the board 31 (the longer-scale directionof the board 31 in FIG. 17), by thermal expansion due to a difference inlinear expansion coefficient between the electronic component 32 ofceramic or the like and the epoxy resin board 31.

Accordingly, when the linear expansion coefficient of the board 31 inthe longitudinal direction in which the terminal electrode 32 and theelectrode pattern 34 tend to be influenced is small, the influence canbe minimized. This has an advantageous effect of relaxing stress on thesolder 35, suppressing a crack in the solder 35, and improving heatcycle resistance performance.

[Four-Terminal Electrode Patterns: FIG. 20]

Four-terminal electrode patterns are described below, with reference toFIG. 20. FIG. 20 is a schematic view showing the four-terminal electrodepatterns.

The arrangement of the four-terminal electrode patterns is determined inaccordance with the shape of the electronic component 32 mounted.

In detail, in the case where terminal electrodes are provided at cornersof the rectangular electronic component 32 and electrode patterns 34 ato 34 d connected to the terminal electrodes are formed on the board 31,a direction in which the electrode patterns 34 a and 34 b formed atpositions corresponding to corners on one shorter side of the electroniccomponent 32 face the electrode patterns 34 c and 34 d formed atpositions corresponding to corners on the other shorter side of theelectronic component 32 is set to match the longitudinal direction ofthe board 31.

In other words, a direction in which the electrode patterns 34 a and 34c or the electrode patterns 34 b and 34 d formed at positionscorresponding to corners on the same longer side of the electroniccomponent 32 face each other is set to match the longitudinal directionof the board 31.

The above-mentioned arrangement of the four-terminal electrode patternshas an advantageous effect of relaxing stress on solder, suppressing asolder crack, and improving heat cycle resistance performance.

[Another Embodiment According to Fourth Group: FIG. 21]

An oscillator according to another embodiment (another oscillatoraccording to the fourth group) is described below, with reference toFIG. 21. FIG. 21 is a section view of the oscillator according toanother embodiment in the fourth group.

As shown in FIG. 21, in another oscillator according to the fourthgroup, a projection (protrusion) is formed on the electrode pattern 34at a part of contact with the terminal electrode 33 so that the solder35 forms a fillet, based on the structures in FIGS. 17 to 20.

In detail, the projection formed on the electrode pattern 34 enables aspace to be created under the terminal electrode 33, and the solder 35rises up in the space by reflow and forms a fillet. Thus, the strengthof the solder 35 can be enhanced. This has an advantageous effect ofsuppressing a solder crack and improving heat cycle resistanceperformance.

In the oscillator in FIG. 21, too, the electrode patterns 34 arearranged in the direction (longitudinal direction) with the smallestlinear expansion coefficient of the board 31 in FIGS. 17 to 20. Hence,another oscillator according to the fourth group equally has anadvantageous effect of relaxing stress on the solder 35 due to adifference in linear expansion coefficient between the board 31 and theelectronic component 32 and suppressing a crack in the solder 35.

[Advantageous Effect of Embodiment According to Fourth Group]

In the oscillator according to the fourth group, the direction in whichthe two-terminal electrode patterns 34 formed on the epoxy resin board31 face each other is set to match the direction in which the linearexpansion coefficient of the board 31 is small. This has an advantageouseffect of relaxing stress on the solder 35 applied onto the electrodepatterns 34 due to a temperature change, suppressing a crack in thesolder 35, and improving heat cycle resistance performance.

In the oscillator according to the fourth group, regarding thefour-terminal electrode patterns 34 a, 34 b, 34 c, and 34 d formed onthe epoxy resin board 31, the direction in which the electrode patterns34 a and 34 c or the electrode patterns 34 b and 34 d at the positionscorresponding to the corners on the same longer side of the electroniccomponent 32 face each other is set to match the direction in which thelinear expansion coefficient of the board 31 is small. This has anadvantageous effect of relaxing stress on the solder 35 applied onto theelectrode patterns 34 due to a temperature change, suppressing a crackin the solder 35, and improving heat cycle resistance performance.

In another oscillator according to the fourth group, based on thestructure of the above-mentioned oscillator, the projection is formed oneach electrode pattern 34 at the part connected to the correspondingterminal electrode 33 to create a space between the terminal electrode33 and the electrode pattern 34, and the solder 35 forms a fillet in thespace. This has an advantageous effect of enhancing the strength of thesolder 35, suppressing a crack in the solder 35, and improving heatcycle resistance performance.

The present invention is suitable for an oscillator that can suppress asolder crack caused by a temperature change by a simple structure at lowcost and improve heat cycle resistance performance.

1-20. (canceled)
 21. An oscillator including an epoxy resin board and anelectronic component mounted on the board, comprising: an electrodepattern formed on the board; a solder resist formed so as to partiallycover the electrode pattern on a side closer to a center of theelectronic component; and mount solder for solder-connecting theelectrode pattern and a component electrode formed at an end of theelectronic component, in a state where the electronic component islifted by the electrode pattern and the solder resist to create a spacebetween the electrode pattern and the component electrode.
 22. Theoscillator according to claim 21 applied to an oven controlled crystaloscillator.
 23. A manufacturing method of an oscillator including anepoxy resin board and an electronic component mounted on the board,comprising: forming an electrode pattern on the board; forming a solderresist so as to partially cover the electrode pattern on a side closerto a center of the electronic component; applying solder onto theelectrode pattern; mounting the electronic component on the solderresist; and solder-connecting the electrode pattern and a componentelectrode formed at an end of the electronic component by reflow, in astate where the electronic component is lifted by the electrode patternand the solder resist to create a space between the electrode patternand the component electrode.
 24. An oscillator including an epoxy resinboard and a circuit component mounted on the board, comprising:two-terminal electrode patterns formed on the board and solder-connectedto terminal electrodes of the circuit component; a projection formed oneach of the electrode patterns at a part of contact with a correspondingterminal electrode; and solder applied onto the electrode pattern,wherein a tip of the projection contacts the terminal electrode, and thesolder is filled in a space between the electrode pattern and theterminal electrode and, as a result of reflow after the circuitcomponent is mounted, forms a fillet between the electrode pattern and aside surface of the terminal electrode.
 25. The oscillator according toclaim 24, wherein the projection is formed on the electrode pattern on aside closer to the other electrode pattern facing the electrode pattern.26. The oscillator according to claim 24, wherein the solder forms thefillet in a space on the electrode pattern where the projection is notformed.
 27. The oscillator according to claim 24, wherein a plurality ofprojections are provided on each of the electrode patterns.
 28. Theoscillator according to claim 24, wherein the two-terminal electrodepatterns are arranged so that a direction in which the electrodepatterns face each other matches a direction in which the board has asmallest linear expansion coefficient.
 29. The oscillator according toclaim 24 applied to an oven controlled crystal oscillator.
 30. Anoscillator including an epoxy resin board and an electronic componentmounted on the board, comprising: an electrode land pattern formed onthe board; a dummy land pattern formed on the board where the electroniccomponent is mounted; a solder resist formed so as to cover the dummyland pattern; a silk print layer formed so as to cover the solderresist; and mount solder for solder-connecting the electrode landpattern and a component electrode formed at an end of the electroniccomponent, in a state where the electronic component is lifted by thedummy land pattern, the solder resist, and the silk print layer tocreate a space between the electrode land pattern and the componentelectrode.
 31. The oscillator according to claim 24 applied to an ovencontrolled crystal oscillator.
 32. A manufacturing method of anoscillator including an epoxy resin board and an electronic componentmounted on the board, comprising: forming an electrode land pattern onthe board and a dummy land pattern on the board where the electroniccomponent is to be mounted; forming a solder resist so as to cover thedummy land pattern; forming a silk print layer so as to cover the solderresist; applying solder onto the electrode land pattern; mounting theelectronic component on the silk print layer; and solder-connecting theelectrode land pattern and a component electrode formed at an end of theelectronic component by reflow, in a state where the electroniccomponent is lifted by the dummy land pattern, the solder resist, andthe silk print layer to create a space between the electrode landpattern and the component electrode.